Conventional pneumatic tires are normally provided with a carcass formed from at least one layer including a plurality of cords along the inner circumference of the pneumatic tire. In recent years, further weight reduction of pneumatic tires has been desired. Consequently, pneumatic tires having the carcass separated at the tread portion have been suggested (Patent Documents 1 and 2). Such pneumatic tires can reduce the cords used in the carcass only by the part included in the segmented portion segmented at the tread portion. In this way, reduction in weight is thereby possible.
Also, not segmenting the carcass over the whole circumference, but providing an outlined portion wherein the carcass cords are not extended at a plurality of places located at intervals in the circumferential direction of the tread in an area where the carcass is overlapped with a belt has been proposed (Patent Document 3).
Furthermore, covering the carcass segmented portion with a carcass reinforcing layer formed from one layer including metallic cords parallel or almost parallel with at least the metallic cords of the above mentioned carcass has been proposed (Patent Document No. 4).    Patent Document 1: Japanese Unexamined Patent Application Publication No. H10-157408    Patent Document 2: Japanese Unexamined Patent Application Publication No. 2001-347808    Patent Document 3: Japanese Unexamined Patent Application Publication No. 2001-233016    Patent Document 4: Japanese Unexamined Patent Application Publication No. 2007-196746